WASHINGTON, AND MARION COUNTIES. 



in very moist situations ; the yellow- wood grows for some 

 distance only on the moist talus from the cliffs of Dix and 

 Kentucky rivers We have not in the region seen a single 

 birch ; and its absence seems remarkable. The willows are, 

 of course, moisture-loving trees; but it seems impossible to 

 determine now whether they were indigenous. 



When we come to study the distribution ot species over the 

 different geological formations of the region, we have a sub- 

 ject which is worthy of a more careful investigation than it has 

 received. It is a subject which should be studied separately 

 and with ample time. When all the observing powers can be 

 thus given to one subject, the mind is not distracted and every 

 minute fact is noted. 



In the Reports made on the Geology of the various coun- 

 ties represented in this region, the rocks were divided into the 

 following groups : beginning with the upper and ending with 

 the lower : 



Carboniferous, 



Devonian, 

 Upper Silurian, 



Lower Silurian, 





Coal Measures. 



Upper Subcarboniferous. 



Lower Subcarboniferous. 



Black Slate. 



Corniferous Limestones. 



Crab Orchard Shales. 



Medina Sandstone. 

 ~ ( Upper Hudson River Beds. 



Middle Hudson River Beds. 



Lower Hudson River Beds. 



Trenton Limestones. 



Birdseye Limestones. 

 ^ Chazy Limestones. 



Chazy Limestones. — This series of rocks is only seen 

 in the steep escarpments which rise above Kentucky river, 

 Dix river, and some of the smaller streams that enter them, 

 and the conditions would not seem favorable for preserv- 

 ing any marked characteristics in the distribution of plants. 

 But even here some peculiarity is observed. On no other 

 soils have we been able to see any individual of the follow- 

 ing species : yellow-wood, wafer-ash, round-leaved catchfly, 



